Various types of clamping devices have been known in the past for releasably securing the support rod of a hanger, stirrup, arm support, or other accessory to the side rail or track of a medical table. Two such devices are illustrated in U.S. Pat. Nos. 3,046,072 and 3,339,913. Such clamps and others like them are intended to perform two separate clamping functions, one being the clamping attachment to the rail or track and the other being the clamping connection to the upstanding support rod of the accessory.
An effective clamp must not only provide secure attachment but must be easily and quickly adjustable. While prior clamping structures have usually satisfied one of these requirements, there has been an apparent lack of success in satisfying both. At the same time, power-operated medical tables have become more complex with articulated sections capable of being shifted into a wide variety of positions, thereby adding a further requirement to clamp operation, specifically, that the clamp be capable of a swivel action so that it may be adjusted to maintain the accessory support rod in vertical position (or in any other selected position of adjustment) as the patient-supporting sections of the table are repositioned. Once the support rod has been swiveled into its selected position, the clamp should be capable of being easily and quickly manipulated to lock the accessory in that position.
A main aspect of this invention lies in providing an improved clamp which may be easily manipulated by one hand to perform all three functions and, when tightened, may be relied upon to maintain the accessory in its selected position of adjustment. Since one-handed manipulation of the clamp is so readily achieved, the user's other hand is left free to hold and reposition (if necessary) the accessory. The result is a reliable and compact clamp mechanism that may be operated by one person without difficulty even though multiple adjustments must be made and the accessory itself must be supported while such adjustments are taking place.
Briefly, the clamp includes a generally cylindrical body having a cup section and a base section, the two sections being disposed in axial alignment and having a pair of opposing first ends provided with annular rows of teeth arranged to lock the two sections against independent relative rotation when their teeth are in intermeshing engagement. The cup section has a centrally-apertured transverse wall adjacent its first end and a chamber leading from that wall to an opening at the opposite (second) end of the cup section. Through the chamber extends a hollow stem which is rigidly secured at one end to the base section of the clamp. A first operating knob is threaded upon the free end portion of the stem and includes a cylindrical shank that projects into the chamber. A thrust bearing is held against the end of the shank by a compression spring disposed within the chamber, the spring also performing the function of urging the two sections of the clamp into intermeshing engagement. A pair of aligned openings formed in the cylindrical side wall of the cup section receive the support rod of the accessory to be mounted upon the medical table, such openings being generally triangular in shape so that as the first operating knob is tightened to drive the thrust bearing into engagement with that portion of the rod extending through the chamber, the rod will be wedged tightly in place within those openings. Tightening or loosening the first operating knob performs the dual functions of locking or releasing both the support rod of the accessory and the swivel mechanism, thereby allowing both longitudinal adjustment of the support rod and rotational adjustment of that rod into vertical position, horizontal position, or any selected position of inclination therebetween. A second control knob, coaxial with the first knob and disposed immediately adjacent to it, is carried by an operating shaft that extends through both sections of the clamp and terminates in a shoe located at the free end of the base section. Upon rotation of the second knob, the shoe may be shifted to engage or release the channel track extending along the side of the medical table. The shoe is spring-loaded towards a releasing position so that when the second knob is rotated to relieve the clamping force exerted upon the track, the entire clamp may be shifted along that track without objectionable restraint or noise.
Other features, advantages, and objects of the invention will become apparent from the specification and drawings.